A wireless power transmission or a wireless energy transfer refers to a technology of wirelessly transferring electric energy to desired devices. In the 1800's, an electric motor or a transformer employing the principle of electromagnetic induction has been extensively used and then a method for transmitting electrical energy by irradiating electromagnetic waves, such as radio waves or lasers, has been suggested. Actually, electrical toothbrushes or electrical razors, which are frequently used in daily life, are charged based on the principle of electromagnetic induction. The electromagnetic induction refers to a phenomenon in which voltage is induced so that current flows when a magnetic field is varied around a conductor. Although the commercialization of the electromagnetic induction technology has been rapidly progressed around small-size devices, the power transmission distance is short.
Until now, wireless energy transmission schemes include a remote telecommunication technology based on resonance and a short wave radio frequency in addition to the electromagnetic induction.
Recently, among wireless power transmission technologies, an energy transmitting scheme employing resonance has been widely used.
In a wireless power transmission system employing electromagnetic induction or resonance, since power is transferred through coils of the wireless power transmitter and the wireless power receiver, a user may easily charge electronic appliances such as a portable device.
In addition, the wireless power transmitter of the wireless power transmission system includes a magnet for aligning with the wireless power receiver. The relative positions of the coils of the wireless power transmitter and the wireless power receiver may be guided by the magnet provided inside a transmission coil of the wireless power transmitter, such that the coils of the wireless power transmitter and the wireless power receiver are aligned with each other, thereby improving the power transmission efficiency.
However, according to the related art, when the magnet provided to the transmission coil of the wireless power transmitter is inserted into an inside of the transmission coil, a reverse magnetic field generated from the magnet is offset against a magnetic field generated from a magnetic substance of the wireless power receiver to increase a saturation current, so that the magnetic substance may be saturated, thereby deteriorating a property of the magnetic substance. When the property of the magnetic substance is deteriorated, a property of the reception coil, that is, the inductance L and the resistance R of the reception coil may be varied, so that the quality factor (Q=W*L/R) of the reception coil may be reduced. Since, when the value of Q of the reception coil is reduced, the power transmission efficiency between the wireless power transmitter and the wireless power receiver may be reduced, there is a need to prevent the magnet from exerting an influence on the magnetic substance.